CVE-2026-48710
Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP `Host` request header was not validated before being use
CVSS
6.5
Medium
EPSS
1.4%
p70
KEV
—
Exploit Today
21
0-100
Published: May 26, 2026 · Last modified: Jul 15, 2026 · CWE-444 · CWE-1289
Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP `Host` request header was not validated before being used to reconstruct `request.url`. Because the routing algorithm relies on the raw HTTP path while `request.url` is rebuilt from the `Host` header, a malformed header could make `request.url.path` differ from the path that was actually requested. Middleware and endpoints that apply security restrictions based on `request.url` (rather than the raw `scope` path) could therefore be bypassed. Users should upgrade to a version greater than or equal to version 1.0.1, which validates the `Host` header against the grammar of RFC 9112 §3.2 / RFC 3986 §3.2.2 when constructing `request.url` and falls back to `scope["server"]` for malformed values.
- badhost.orghttps://badhost.org
- github.comhttps://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6
- github.comhttps://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
- github.comhttps://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml
- ostif.orghttps://ostif.org/disclosing-the-badhost-vulnerability-in-starlette
- www.secwest.nethttps://www.secwest.net/starlette
- www.x41-dsec.dehttps://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:22992
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:22993
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:23346
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:24866
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:26226
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:30088
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:30089
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:34456
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:34526
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:34532
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:37275
- access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-48710
- bugzilla.redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2481742